Flowerhorns need to be the dominant fish to really thrive, so if your readhead is 7" thats why the fh is hiding unless u just got him recently. If it's a new fish he probably needs a few weeks to settle in and start trusting u, but either way you're probably gonna have to remove the other cichlid or add more fish to disperse aggression.
That being said, flowerhorns aren't typically "glass bangers" unless they're spawning. Fh's are one of the most owner responsive fish IMO but won't try to constantly kill u like a midas would. Sure they'll bite ur finger if u stick it in the tank or rip apart most other fish their size, but the only time my fh ever attacked me was when I tried moving an airstone after they laid eggs. Every other time I walk up to the tank he greets me by showing off his fins for food, and that was the dominant male out of 8 siblings. Their father was the same way along with every other fh I've raised. Some are shy and relatively peaceful, others are territorial and won't tolerate any tankmates. Their unique personalities really begin to show around the 4" mark so yours should hopefully start coming out soon
